| 摘要 |
PURPOSE:To prevent air from remaining in a mold so as to prevent the surface of a sponge roll from having irregularities thereby improving the function and appearance, by differenciating the thickness of a tubular mold for molding a sponge roll, and making the thermal conductivity of the part around the central section of the mold greater the part around the opposite ends of the mold. CONSTITUTION:A roll stem 1 covered with an unfoamed rubber layer 2 is placed in a mold 3 is secured firmly with the roll stem 1 inserted through holes in side plates 4, 4'. Then the mold 3 is heated by a suitable external heating source such as a hot current to allow the unfoamed rubber layer 2 to foam and at the same time to allow the layer 2 to be molded and fused to the roll stem 1 thereby molding a sponge roll in comformity with the inner circumferential surface of the mold 3. The thickness of the pipe wall of the tubular mold 3 around the central section 3a thereof is reduced than that around the opposite sections 3b, 3b'. Through-holes 5 for discharging the released gas formed in the side plates 4, 4' are in communication with a space 6 formed between the unfoamed rubber layer 2 and the mold 3. The gas released in any part of the unfoamed rubber layer can be allowed to be discharged to the outside of the mold through the through-holes formed in the side plates. |
